<!DOCTYPE html>
<html lang="en">    
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      #result {
        width: 200px;
        height: 200px;
        border: 1px red solid;
      }
    </style>
  </head>
  <body>
    <div id="result"></div>
    <script>
      //绑定键盘按下事件
      window.onkeydown = function () {
        //发送请求
        const xhr = new XMLHttpRequest();

        //这里是自动转化响应体里面的json
        //设置响应体数据的类型
        xhr.responseType = "json";

        //初始化并传入url
        xhr.open("GET", "http://127.0.0.1:7000/json-server");

        //发送
        xhr.send();

        //事件绑定，处理返回结果
        xhr.onreadystatechange = function () {
          if (xhr.readyState === 4) {
            if (xhr.status >= 200 && xhr.status < 300) {
              //1.这里是手动转化
              //   let data = JSON.parse(xhr.response);
              //   console.log(data);
              //   result.innerHTML = data.name;

              //2.自动转化的步骤在代码26行
              console.log(xhr.response);
              result.innerHTML = xhr.response.name;
            }
          }
        };
      };
    </script>
  </body>
</html>
